Nothing in life is free, it just so happens that flying is every so slightly
more expensive than many other interests.
You'll never know if you don't try, but only you can make the decision on whether or not to continue. If you are worried about the expense, why not leave it for a couple of years and see if you want to do it then? At 17, the world is your oyster and there are an awful lot of things to see and do, so why not have a look around at other options? If nothing else compares favourably to flying, then you can always come back to it.
Also, find your local EAA chapter (
www.eaa.org), go and hang out at their local get-togethers. You might get a better idea of what a future in aviation could hold for you, as well as finding other parts of aviation that interest you.
Just one more thing, don't rely on the aviation industry being "normal" when you are ready to job hunt - I doubt very much that there is a "normal" for the aviation industry.